Dozens of people in Chisinau are protesting the detention of the mayor of Moldova's second-largest city on suspicion of violating privacy laws after he published a telephone conversation between the former prime minister and a businessman.

Renato Usatii, the pro-Russian mayor of Balti, published a telephone conversation on October 23 on his Facebook page between a businessman and former Prime Minister Vlad Filat, who was arrested this week and charged with taking a $260 million bribe.

Prosecutors said in a statement that Usatii was detained on October 23 at Chisinau airport for illegally intercepting a telephone conversation, a charge that carries a punishment of up to three years in prison.

Usatii's party was banned from taking part in the November 2014 parliamentary election because it received money from abroad.

Usatii fled Moldova, saying he feared arrest, but later returned to run for mayor of Balti.